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Stormwalker

Blowers for Ribbon Burners

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Can anyone recommend a cost effective blower that could be used with a ribbon burner?  I know that most require 5 lbs. of static pressure.  I also know that blowers are available from some of the blacksmith supply houses.  But I would like to find a suitable alternative that didn't cost $140 per copy at the start.  Like everyone I want to walk the line between spending what is necessary and not over spending.  From my research, it seems I would be looking for a centrifugal blower, that has the necessary sp to run the ribbon burner. Can anyone make some recommendations on where they have sourced alternative blowers from and what type of equipment they were aquired from?

Thanks,

Storm

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You need to read the information available from these people http://www.pineridgeburner.com/.    In their products they have both low pressure and high pressure ribbon burners.

While it may seem a simple thing design in any burner type contains a lot of hidden  gottcha.   Their low pressure burners measure pressure in inches of water! 

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Welcome aboard Storm, glad to have you. If you'll put your general location in the header you might be surprised how many of the IFI gang live within visiting distance.

If you check Grainger or McMaster Carr they have blowers in many sizes and ranges.

I'm not a gun burner guy but with my experience a high static pressure tells me the burner nozzles are too small or restrictive. Maybe put more nozzles in the ribbon? 2x as many = 1/2 the pressure.

Just be aware that's an educated guess from a long time tinkerer who's been kicking around a naturally aspirated ribbon burner concepts but has NOT made one. So it's a FWIW idea.

Frosty The Lucky.

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Storm, You can look around for one of the blowers that are used to blow up Santa and Frosty (the snowman not our Frosty The Improbable.  He has enough hot air already).  You can check e-bay, craigslist, flea markets, etc.  You might even try a shop vac with the hose on the exhaust. www.BlacksmithDepot.com has two.  I have the larger one but the smaller one will work.  From the looks of your post it appears that you have already checked there.  I tell people that generally a common squirrel cage fan will not develop the required pressure, but if you already have one try it.  If it works great and if it doesn't then you are not out anything and then you can keep searching.

 

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Hey I RESEMBLE that remark!!  :o

Frosty The Lucky.

Edited by Frosty

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I'm not a gun burner guy but with my experience a high static pressure tells me the burner nozzles are too small or restrictive. Maybe put more nozzles in the ribbon? 2x as many = 1/2 the pressure.

Just be aware that's an educated guess from a long time tinkerer who's been kicking around a naturally aspirated ribbon burner concepts but has NOT made one. So it's a FWIW idea.

Frosty The Lucky.

Flow and pressure are actually related by a square law: Flow through an orifice will vary in proportion to the square root of the pressure.

Double the hole area and you'll have halve the flow per hole and only need one quarter of the pressure.

Frosty's suggestion of doubling the number of holes is preferable to making the holes bigger because there is a greater likelihood of the flame travelling back down a bigger hole. It's largely down to the relationship between the wall of the hole and its volume. 

Higher pressures tend to mean higher velocities through whatever is doing the job of a burner nozzle, reducing the risk of flashback. In a ribbon burner, the holes through the refractory are doing the job of burner nozzles.

If you modify a known good burner design to run at lower pressure (or even run one below the pressure it is known to work at), you increase the risk of flashback. Flashback happens when the speed of the flame-front through the mixture exceeds the speed the mixture is moving in the opposite direction through the nozzle. In most burners, it's not a big deal because there is not very much mixture upstream of the nozzle. Ribbon burners tend to have a plenum, often with a significant volume of gas/air mixture in, so there's more potential for a bigger bang.

There's quite a lot more to burner design than it initially appears.

 

 

 

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Let me see if I have this straight. Double the area of the hole halves the flow velocity and quarters the pressure. Yes?

Does the volume of gas delivered not double? OR is that a constant?

Frosty The Lucky.

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I recently made a ribbon burner and use crayons foe the holes. I bought the 164 cfm blower from blacksmiths depot. I have to choke the blower way down to almost closed to run the burner even at welding heat. If I want to really put the heat on I Crack the choke to 1/3 open and turn the gas up and that is when the forge is so hot you cannot even see detail inside without wearing sunglasses. One possible route is to order a dayton blower from amazon and if it doesn't work, just return it without losing a dime. I lost power to my blower once and all that happened was that there were large slow orange flames spewing from the forge.

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Let me see if I have this straight. Double the area of the hole halves the flow velocity and quarters the pressure. Yes?

Does the volume of gas delivered not double? OR is that a constant?

Frosty The Lucky.

That's it, yes.

They are all related, so adjusting any one will have an effect on one of the others. 

If you keep the flow (volume) the same and double the hole area (as suggested in post #3) the pressure will drop to one quarter. 

If you keep the pressure the same and double the hole area, you'll double the flow.

 

I'm more familiar with Naturally Aspirated burners than blown burners, but the basic Physics applies to both.

Most of the Naturally Aspirated burners out there have fixed gas jets, so simply follow the square law for flow (and therefore BTU/hr) vs pressure.

If you double the pressure, the flow will increase by around 41% (the square root of 2 is about 1.41).

If you halve the pressure, the flow will reduce by about 29% (the square root of 1/2 is about 0.707). 

 

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Thanks Tim. I've had an intuitive grasp as a rule of thumb but tune the things by ear and eye. Before the accident I was going to play around making a naturally aspirated chip forge and now my urge to tinker is fixing on a ribbon burner. I just don't mess with stuff like I did before the tree got me.

I still like knowing what's going on. I don't necessarily need to know the math just what factors are at work.

Frosty The Lucky.

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Thank you all for the replies!  

From what I have been able to determine, ( and it has been stated here and in other posts ) is to keep the air/fuel mixture velocity in the ribbon burner higher than the speed of the flame front travel back through the ribbon burner,  as long as this balance is maintained, then there should never be combustion on the wrong ( manifold )  side of the burner.

78SharpShooter,  Thank you so much for the observed performance of your forge and blower combination.

 

Storm

 

Edited by Stormwalker

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